It is known to produce compositions for use in screen printing screens which are diazonium compound-sensitized polyvinyl alcohol/polyvinyl acetate emulsions. Such emulsions have several drawbacks in that the shelf life is so limited that they should be prepared as a two-component system and not mixed until immediately prior to usage. Besides the inconvenience of doing so, a further drawback is that unless the diazonium compound is thoroughly mixed into the emulsion, there may be uneven sensitization of the emulsion in that some areas are more heavily sensitized than others. In addition, depending upon the ratio of polyvinyl alcohol to polyvinyl acetate, the emulsion may be used with either solvent-based inks or water-based inks, but generally not with both.
It is desired to produce a composition for use in a screen printing screen which has a shelf life sufficient to allow it to be prepared as an one-component system. It is also desired to produce a composition for use in screen printing screen which is relatively insensitive to both water and a variety of organic solvents thus making it useful for a variety of inks, both waterbased and solvent-based, and which is relatively oxygen insensitive, elimating the need to expose a screen prepared with a protective barrier layer.